Patents by Inventor Ram S. Ramanujam

Ram S. Ramanujam has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7444615
    Abstract: A method for generating an OPC model is provided which takes into consideration across-wafer variations which occur during the process of manufacturing semiconductor chips. More particularly, a method for generating an OPC model is provided which takes into consideration across-wafer variations which occur during the process of manufacturing semiconductor chips based on the parameters of test patterns measured at the “wafer sweet spots” so as to arrive at an accurate model.
    Type: Grant
    Filed: May 31, 2005
    Date of Patent: October 28, 2008
    Assignee: Invarium, Inc.
    Inventors: Gokhan Percin, Ram S. Ramanujam, Franz X. Zach, Abdurrahman Sezginer, Chi-Song Horng, Roy Prasad
  • Patent number: 7318214
    Abstract: The present invention provides a system and method of modifying the mask layout shapes of an integrated circuit layout design to compensate for reticle field location-specific systematic CD variations resulting from mask writing process variations, lens imperfections in lithographic patterning, and photoresist process variations. Called PLC (Process-optimized Layout Compensation), each set of compensation rules according to the present invention is specifically tailored for a particular mask-writer-patterning-tools-and-resist-process combination, and are performed on a reticle-wide basis. Furthermore, for each geometric shape in the mask layout, the amount of modification is determined based on a categorization of the type of the shape, the specific location in the reticle field the particular shape falls in, its context (i.e., surrounding patterns, orientation, etc.), as well as certain photoresist parameters to be used in the patterning process.
    Type: Grant
    Filed: May 7, 2004
    Date of Patent: January 8, 2008
    Assignee: Invarium, Inc.
    Inventors: Roy V. Prasad, Chi-Song Horng, Ram S. Ramanujam